It is nowadays no longer possible to imagine modern medicine without minimally invasive procedures. In the field of resectoscopy, in which harmful or damaged tissue is removed (e.g. from the prostate), particular use is made of resectoscopes that have a high-frequency cutting means with which tissue is ablated by high-frequency currents. An advantage of tissue ablation by means of high-frequency currents is that bleeding at the operating site can be rapidly staunched.
DE 2006 039 696 A1 discloses a device for resection and/or ablation of organic tissue by means of high-frequency current. The device comprises a coil, which can be subjected to a high-frequency voltage, and a coil carrier, which is configured as a cylindrical hollow tube. The coil is arranged at a distal end of the coil carrier, wherein a coil end portion of the coil and a distal connecting element portion form a wedge-shaped cutting edge to which the high-frequency voltage can be applied. Since the coil is made of an electrically conductive wire, it can deform at the operation site even under the action of a slight force, which makes precise ablation of tissue difficult.
DE 693 33 489 T2 discloses a medical probe device which comprises a catheter and a flexible stylet, wherein the stylet is guided in a corresponding guide housing. For tissue ablation, a high-frequency electrode (also referred to sometimes as a needle) can be arranged on the stylet. Although said device brings with it a great many additional possibilities, mechanical ablation of tissue is again not possible here, since the high-frequency electrode deforms at the application site even under the action of a slight force.
EP 2 298 204 B1 from the applicant discloses a medical instrument for bipolar electrosurgery, with an outer shaft, at the distal end of which an electrically conductive blade is arranged which is insulated from the outer shaft, and with a working insert which is received in the outer shaft and can be moved axially to and fro in the latter and, at its distal end, has a hook with a cutting edge directed outward in the proximal direction. In a deployed position of the working insert, tissue can be gripped by the hook and can be moved in the direction of the blade by pulling the working insert into the outer shaft. When a high-frequency current is applied to the hook and blade, tissue held between them is coagulated. By pulling the working insert farther into the outer shaft, it is also possible to separate tissue. Since the cutting edges of hook and blade are at an angle to each other, a scissor-like cutting movement can be executed between the cutting edges of hook and blade. However, the construction and the operating behavior of this medical instrument are relatively complicated.
Moreover, the prior art also discloses cutting instruments for minimally invasive surgery which are secured on an outer shaft of an endoscope, resectoscope or a needle.
U.S. Pat. No. 6,245,011 B1 discloses such an endoscopic cutting instrument comprising a radially adjustable blade which is arranged at a distal end of the outer shaft of the instrument and can be deployed radially beyond the outer shaft such that, by means of a rotational movement, it can be used to cut in a circumferential direction.
In summary, the instruments from the prior art have in particular the disadvantage that no mechanical ablation of tissue is possible in an axial direction.